“…For these reasons, we propose a threshold-based semiautomatic segmentation method to generate ROI segmentations from lung CT available on COVID-19 Data Archive (COVID-ARC) ( https://covid-arc.loni.usc.edu ) which curates and disseminates multimodal and longitudinal datasets related to COVID-19 [ 22 ]. This segmentation method is used to calculate the percentage of lung abnormality (PLA) to determine COVID-19 severity and improve analysis of disease progression in follow-up CT.…”